The present invention relates to speed shift indicating devices for motor vehicles driven by an internal combustion engine and which have a manually controlled transmission. The speed shift indicating device provides an indication to the driver of the optimum point at which to shift the manual transmission.
In motor vehicles having a manual shift transmission, it is highly desirable to provide some device which indicates the optimum point at which to shift. By shifting when the engine speed reaches a predetermined value, maximum acceleration may be obtained, and damage caused by excessive engine speed can be avoided.
Many drivers of high performance vehicles such as sports or race cars purchase relatively expensive tachometers to assist them in shifting the transmission at the optimum point. These tachometers often have needles or movable indicators which must be watched to determine when the desired shift point is reached. These devices, however, tend to distract the driver's attention from the road. Furthermore, they are often expensive and require an appreciable amount of work to install them in the vehicle.
In the past, devices have been proposed which would indicate to the driver by means of an indicator light or buzzer when he should shift gears. Examples of such devices are described in U.S. Pat. Nos. 3,420,328 by Johnson et al; 3,603,878 by Himmelstein; 3,719,888 by Sampey; and 3,909,619 by Kniesley et al. One problem with the prior art devices has been that they have either required a relatively large number of components, required elaborate modification of the automobile for installation, or are intended for original equipment in the automobile. There remains a definite need for an arcuate, low-cost, compact, simple-to-install speed shift indicator which is adaptable to a wide variety of vehicles and both electro-mechanical and electronic ignition systems.